We present new 450 and 850 \mu m SCUBA data of the dwarf galaxy NGC 1569 .
We construct the mid-infrared to millimeter SED of NGC 1569 , using ISOCAM , ISOPHOT , IRAS , KAO , SCUBA and MAMBO data , and model the SED in order to explore the nature of the dust in low metallicity environments .
The detailed modeling is performed in a self-consistent way , synthesizing the global ISRF of the galaxy using an evolutionary synthesis model with further constraints provided by the observed MIR ionic lines and a photoionisation model .
Our results show that the dust properties are different in this low metallicity galaxy compared to other more metal rich galaxies .
The results indicate a paucity of PAHs probably due to the destructive effects of the ISRF penetrating a clumpy environment and a size-segregation of grains where the emission is dominated by small grains of size \sim 3 nm , consistent with the idea of shocks having a dramatic effect on the dust properties in NGC 1569 .
A significant millimetre excess is present in the dust SED which can be explained by the presence of ubiquitous very cold dust ( T = 5 - 7 K ) .
This dust component accounts for 40 to 70 \% of the total dust mass in the galaxy ( 1.6 - 3.4 \times 10 ^ { 5 } M _ { \odot } ) and could be distributed in small clumps ( size \simeq a few pc ) throughout the galaxy .
We find a gas-to-dust mass ratio of 740 - 1600 , larger than that of the Galaxy and a dust-to-metals ratio of 1 / 4 to 1 / 7 .
We generate an extinction curve for NGC 1569 , consistent with the modeled dust size distribution .
This extinction curve has relatively steep FUV rise and smaller 2175 Å bump , resembling the observed extinction curve of some regions in the Large Magellanic Cloud .